1. Field of the Invention
The present invention relates to a lamp, and more particularly, to a lamp having illumination modules with different percentages of luminance adjustment.
2. Description of the Prior Art
In current working environments, displays are heavily-used and almost replace paper to become the major media for displaying information. A display used in such a working environment is called a visual display terminal (VDT). According ANSI/HFS 100 (American National Standards Institute/Human Factors Society 100), a suggested illumination for a VDT environment is 300 to 500 lux. Please refer to FIG. 1. FIG. 1 illustrates a situation while a prior art lamp 10 is used. When the lamp 10 is used on a desktop 20 and the height H from the desktop 20 to the lamp 10 is 50 centimeters, the illumination of a luminous area 12 is more than 300 lux and meets with the suggested illumination of ANSI/HFS 100 for the VDT environment. The length L1 of the luminous area 12 is about 50 centimeters. However, due to the design of the lamp 10, the illumination outside the luminous area 12 is less than 300 lux, such that the illumination outside the luminous area 12 is not illuminated enough. In this situation, if two or more displays are placed on the desktop 20 or if a user need to write something with hands, the illumination of peripheral area of the desktop 20 would be not enough. Moreover, if the user wants to increase the illumination outside the luminous area 12, one or more lamps are needed to place on the desktop 20. However, the extra lamp on the desktop 20 would reduce the usable space of the desktop 20, and it is more power consumptive than a single lamp.